The ultimate goal of this research is to understand the cellular mechanisms underlying electrolyte and fluid transport in salivary glands. A related goal is to understand how these transport processes are affected in cystic fibrosis. The specific aims are: 1. To use the electron microprobe technique to measure elemental concentrations of Na, Mg, P, S, Cl, K and Ca in basal and apical cytoplasm, secretory granules, nuclei, mitochondria, lateral intercellular spaces and lumen of nonstimulated rat parotid gland acini. 2. To use the electron microprobe technique to measure the above elemental concentrations in the listed intracellular and extracellular spaces following induction of salivation with cholinergic and Alpha and Beta-adrenergic secretagogues. 3. To use the measured Na, Cl and other elemental concentrations listed above to test for the transcellular and paracellular electrolyte changes, and accompanying water fluxes, that are predicted by the solute-solvent coupled hypothesis for water flow in epithelial tissues. 4. To perform similar elemental analyses in intercalated and striated ducts from parotid glands in order to determine if there are appreciable electrolyte or water fluxes across these structures. 5. To perform similar analyses in parotid glands from reserpinized animals to determine how these electrolyte and water transport mechanisms are affected. These findings will contribute to our understanding of salivary gland physiology and of transport changes in the reserpinized rat--a model for cystic fibrosis in man.